A liquid supply member includes a supply path that supplies with the liquid a discharge port that discharges liquid. For example, the liquid supply member is used for an inkjet recording head which is a representative example of a liquid discharge head including the discharge port.
A configuration of an inkjet recording head will be briefly described with reference to FIG. 14A. An inkjet recording head H1001 includes a tank holder unit H1003 and a recording element unit H1002 that discharges ink. The tank holder unit H1003 includes a tank holder H1500 and a supply path plate H1510.
Ink is supplied to a discharge port from an ink tank (not shown) through an ink supply path that is formed in a liquid supply member (ink supply member) included in the tank holder unit H1003 while being guided by the recording element unit H1002.
FIG. 14B is a bottom view of the tank holder H1500. FIG. 14C is a top view of the supply path plate H1510. The tank holder H1500 and the supply path plate H1510 have grooves H1600 for forming the ink supply path. By joining the tank holder H1500 and the supply path plate H1510 together such that the grooves H1600 face each other, the ink supply path is formed in the ink supply member.
A method for joining the tank holder H1500 and the supply path plate H1510 together may be a known method by laser welding disclosed in Japanese Patent Laid-Open No. 2005-096422.
A method for joining the tank holder H1500 and the supply path plate H1510 together by laser welding will be described. First, the tank holder H1500 being capable of absorbing a laser beam and the supply path plate H1510 being transparent to a laser beam are brought into contact with each other by using a pressing jig 510. Referring to FIGS. 14B and 14C, contact portions 600, at which the tank holder H1500 and the supply path plate H1510 are in contact with each other, are provided in a vicinity of the grooves H1600 to surround the grooves H1600. While the tank holder H1500 and the supply path plate H1510 are in contact with each other, the contact portions 600 are irradiated with laser beams and are joined together. Hence, the ink supply path is formed. Since the ink supply path used for the inkjet recording head has a fine structure, the contact portions 600 have fine structures.
A laser-beam irradiation method includes a scanning method and a simultaneous irradiation method.
The scanning method includes decreasing a spot diameter of a laser beam from a laser beam irradiator, scanning an outline of desirable joint surfaces with the laser beam, and irradiating the joint surfaces with the laser beam. When this method is used, the laser beam with a constant beam diameter scans along the contact portions 600 and welds the contact portions 600 with each other. Thus, the contact portions 600 are irradiated with the uniform laser beam, and the members can be uniformly welded with each other. However, since the laser beam scans along the contact portions 600 and welding the contact portions 600 having the fine structures with each other, this work may take a time.
The simultaneous irradiation method includes irradiating desirable joint surfaces simultaneously with laser beams. This method can decrease a time required for welding.
If it is expected that the tank holder H1500 and the supply path plate H1510 are joined together by the simultaneous irradiation method, to simultaneously irradiate the contact portions 600 provided in a vicinity of the grooves H1600 with laser beams, a plurality of laser beam irradiators are arranged along the grooves H1600.
Meanwhile, referring to FIG. 14B, the ink supply member that supplies the inkjet recording head with the ink includes a region (for example, region A) where the grooves H1600 are densely arranged and a region (for example, region B) where the grooves H1600 are sparsely arranged.
FIG. 15 illustrates laser-beam irradiation when the tank holder H1500 and the supply path plate H1510 are welded with each other by the simultaneous irradiation method. FIG. 15 illustrates a portion in the region B in FIG. 14B containing ends in a longitudinal direction of the grooves H1600.
However, if laser welding is performed by the simultaneous irradiation method, and end contact portions near the ends of the grooves H1600 may be insufficiently welded in the region where the grooves are sparsely arranged (region B in FIG. 14B). For example, the insufficient welding may occur by first and second reasons as follows.
For the simultaneous irradiation, referring to FIG. 15, a plurality of laser beam irradiators 501 to 507 (laser beam sources) with substantially uniform laser-beam intensities are arranged at substantially uniform intervals. Laser beams emitted from the laser beam irradiators propagate and spread by predetermined angles from laser beam apertures. Thus, the number of laser beam irradiators that irradiate the end contact portions with the laser beams is smaller than the number of laser beam irradiators that irradiate portions other than the end contact portions. Thus, in the region B in FIG. 14B, a total irradiation amount per unit area with the laser beams for the end contact portions near the ends in the longitudinal direction of the grooves is smaller than a total irradiation amount per unit area with the laser beams for the contact portions other than the end contact portions. This is the first reason for the insufficient welding at the ends. That is, if the intensity of the laser beams is set to attain an irradiation amount that provides proper welding for the contact portions other than the end contact portions, the irradiation amount with the laser beams for the end contact portions may not achieve the proper irradiation amount required for welding.
Also, the expected second reason is that heat is radiated from the end contact portions in the region B by a larger quantity than a quantity of heat radiated from the contact portions other than the end contact portions.
If the supply path formed by welding contains an insufficiently welded portion, ink may leak from the supply path, and as the result, reliability of the inkjet recording head H1001 may be degraded.